+/* Parses a token taking the form of a format specifier and
+ returns true only if successful. Emits an error message on
+ failure. Stores a null-terminated string representing the
+ format type in TYPE, and the width and number of decimal
+ places in *WIDTH and *DECIMALS.
+
+ TYPE is not checked as to whether it is really the name of a
+ format. Both width and decimals are considered optional. If
+ missing, *WIDTH or *DECIMALS or both will be set to 0. */
+bool